This invention relates generally to apparatus for sensing and indicating the level of liquid in a container and, more particularly, to such apparatus for checking for a minimum acceptable liquid level such as, for example, the oil level in the crankcase of an automobile.
The necessity for maintaining minimum oil level in an engine crankcase to insure proper lubrication of the moving parts of an engine is notoriously well known. Maintaining a minimum level of transmission oil is perhaps even more critical, particularly in the case of automatic transmissions which can suffer devastating damage if driven for any distance with a low fluid level. The oil level in an engine crankcase or transmission is traditionally manually checked by means of a dipstick which extends through a tube into the oil reservoir, with the dipstick being manually removed to permit visual inspection of the calibrated oil level indicator scale thereon. The manually removable dipstick, while having been extensively utilized for many years, is nevertheless undesirable inasmuch as it requires direct access to the engine, which access is often rather difficult and unpleasant and hence there is a tendency to omit periodic checking of the oil level. This in turn can result in serious engine damage due to the engine being operated with inadequate quantities of oil for lubricating same. Additionally, for fleet operation carried out by bus lines, trucking companies and the like, in which these critical oil levels are checked on a somewhat routine basis, the cost in labor and time becomes substantial.
It is therefore a primary object of this invention to provide an arrangement for quickly and accurately checking for at least a minimum acceptable liquid level.
It is another object of this invention to provide such an arrangement which can be initiated from a remote location, such as the driver's seat of an automobile.
It is a further object of this invention to provide an arrangement which gives an indication as to whether the liquid level is acceptable, at a remote location such as the dashboard of an automobile.
With the recent advent of on-board microcomputers in an automobile which assumes the burden of providing diagnostic services, it would be desirable to have an oil level sensor assembly which could be "read" by the microcomputer. It is therefore still another object of this invention to provide such a sensor assembly.